1. Field of the Invention
The present invention relates generally to suspension systems for motor vehicles which ensure optimum control of the damping-force characteristic of a shock absorber, and more particularly, to the art of improving riding comfort and stability of a vehicular position during steering operation.
2. Description of the Related Art
In connection with the known suspension systems for motor vehicles which ensure control of the damping-force characteristic of a shock absorber, JP-A 5-330325 shows a suspension control system. This system calculates an absolute speed of vertical vibration of a vehicle body. In accordance with the direction of the absolute speed, the system controls a damping coefficient of a shock absorber such that the contraction-side damping coefficient has a small value whereas the extension-side damping coefficient has a large value, or the contraction-side damping coefficient has a large value whereas the extension-side damping coefficient has a small value. By this, without detecting a relative speed between a vehicle body located above the spring and an axle located below the spring, i.e. a sprung-unsprung relative speed, behavior of the vehicle body, i.e. sprung behavior, due to road input can be restrained.
With this known suspension control system, a damping performance of a motor vehicle can be secured with regard to sprung behavior due to road input. However, with regard to damping of behavior in the roll direction when a great lateral acceleration is applied to the vehicle body during steering operation, a controlling force is insufficient due to a moment of inertia in the roll direction being applied to the vehicle body.
Moreover, if the system is constructed to produce a damping force sufficient to damp roll behavior during steering operation, an excessive damping force is produced with respect to road input, resulting in deteriorated riding comfort during ordinary cruising.
It is, therefore, an object of the present invention to provide suspension systems for motor vehicles which ensure optimum control of the damping-force characteristic of a shock absorber in accordance with every aspect of vehicular behavior occurring during non-steering and steering operations to achieve both steering stability and riding comfort.